ATOM

Chemistry A Final Review Introduction Atoms make up everything around us from the air we breathe to food we eat and even the stars in the sky. The average layman does not know much about the atom but in this paper I will explain what and why they are. A Brief History The word atom comes from the Greek word meaning indivisible. The concept of the atom had its foundations in ancient Greece with Leucippe of Milet. In 420 B.C. his disciple Democrite of Abdere had the concept that atoms were particles in perpetual motion and were invisible because of their infinitely small size, indivisible, solid, eternal because they are perfect, surrounded by an empty space, and having an infinite number of shapes. His theory was exceptionally close to reality, being that it was 420B.C. The Periodic Table Today we know that each atom is made up of three parts, a proton, a neutron and an electron. These atoms combine to make compounds. The most basic atoms are called elements and cannot be broken down any more than they already are. There are currently 118 known elements 90 of them occurring naturally and the other 28 are man made. The elements combine in an infinitesimal amount of ways to make up every thing around us. Created in 1869 by Mendeldiev the periodic table of the elements is how we chart these elements. Each column on the periodic table is categorized by the amount of atoms in its elements outer field. Hydrogen, Lithium, and sodium all being in the same column on the table have the same amount of atoms in their outer field. Since the electrons in the outer field dictate the types of chemical reactions that an atom can have, the atoms in the same column have some of the same properties (chemical reactions). The Proton We already know that atoms are made up of three different parts (protons, neutrons, and electrons) but how do these particles interact.